When packing fragile objects in boxes for shipping or storage, it is often desirable to surround the objects with protective elements which absorb shocks and insulate the objects to prevent damage. Today the most commonly used materials are shaped styrofoam, styrofoam peanuts, shredded paper, urethane foam as used in foam-in-place systems, foam chips, corrugated inserts, or similar items which are light in weight yet absorb shocks. When packing other objects, it is common to add such materials between a container and its contents for void filling. The disadvantage of such items is that they are large in volume, so require a large storage space before use, many of them are environmentally unfriendly, and some are difficult to dispose of. Small items, such as peanuts, tend to sink to the bottom of a box, thereby leaving upper portions of the object packed therein uncovered and unprotected.
Instead of such materials, it has been suggested to use air cushions, also known as air pillows and air bags, for protecting fragile objects and for void filling. These are small plastic bags which are stored in roll form and inflated in the factory as needed. Thus, they require little storage space. However, conventional air cushion machines are complicated and expensive.
One example of a conventional machine for making air cushions operates using a compressor to provide pressurized air to inflate the cushions. Plastic sheaths sealed on both side edges are provided on a roll. The plastic is advanced between two rollers which grip the plastic between them and advance the plastic sheath as they rotate. When they stop rotating, typically by means of a sensor reading a coded symbol printed on the plastic, the sheath is held still. The sleeve is punctured and filled with air, and then the plastic is sealed at both ends, hopefully sealing the puncture at the same time.
Other known devices include a microprocessor for controlling the filling and sealing of the air cushions. These utilize a computerized system to measure the length of the cushion and send a signal to stop advancing the plastic sheath.
These devices are costly, and require precision in the operation of the sensor for stopping the advance of the plastic, as well as accuracy in sealing the cushions. Furthermore, changing the length of the cushions requires printing new rolls of plastic with the symbols for the end of the cushion located a different distance apart.
Accordingly, there is a long felt need for a relatively inexpensive device for making air cushions, and it would be very desirable to have such a device which is simple to manufacture and operate and wherein the length of the cushions can be changed easily without replacing the plastic roll.
Similarly, magazines and articles of mail, as well as powders, grains, granular material, beads, and other small particles and components, are now being packaged in plastic envelopes. The conventional packaging machines generally include a compressed air source, and a plurality of pistons and pneumatic elements, resulting in an expensive and complex device.